Occult virtue and alchemy.
The author of the Summa believes in occult virtue in nature and attributes it to the stars.[1491] He accepts Albertus Magnus’s explanation of the marvelous virtues of gems as due to celestial influence.[1492] He believes that metals are generated in the earth by the same force and are seven in number according to the seven planets, and thinks that this process can be simulated by alchemy.[1493] In discussing that subject Hermes is his chief authority. The Summa terminates by explaining the superiority of steel to iron and listing various salts.[1494]
Brother Giles on the comet of 1264.
Since we have mentioned the comet of 1264, we may note farther that it was the occasion of a treatise by Brother Giles of the Order of Dominicans, on the essence, motion, and signification of comets,[1495] in which he cites Grosseteste De iudiciis and alludes to the death of Pope Urban IV in that year. The comet was seen in the kingdom of France from mid-July to October and “stupefied the minds of many.”
[1421] References to Grosseteste’s works, unless otherwise stated, will be to Ludwig Baur, Die Philosophischen Werke des Robert Grosseteste, Münster, 1912, in Baeumker’s Beiträge zur Geschichte der Philosophie des Mittelalters, Vol. IX. This edition seems to make little effort to correct errors of case or number in the MSS, so that much of the text is far from being smooth reading. Baur discussed Die Philosophie des Robert Grosseteste in Vol. XVIII (1917) of the same series. The life of Grosseteste is treated briefly in DNB, and more fully in the old and pedantic work of Samuel Pegge, The Life of Robert Grosseteste, London, 1793, 385 quarto pages with many foot-notes and appendices, which however are based mainly on the works of preceding antiquaries, the author stating in his preface, “my private station as a country clergyman would not permit me to have much access to public libraries, but the materials were chiefly to be sought for in a book-room which, you will easily suppose, cannot be very richly or amply furnished.” Pegge’s Life was already described in 1861 as “one of the scarcest of modern works”; but the British Museum possesses two copies. Other biographies are by J. Felten, Freiburg, 1887, and F. Stevenson, London, 1889. The letters of Grosseteste, which do not especially concern us, are edited by H. R. Luard in RS XXV, 1861.
Not to be confused with Grosseteste is Robertus Anglicus who wrote a commentary on the Sphere of Sacrobosco in 1271, a Tractatus quadrantis at Montpellier in 1276 (printed 1508), and Canons for the Astrolabe (printed at Colle about 1478): see Duhem, III (1915), pp. 292, 298.
[1422] Brewer, 70 and 75.
[1423] Pegge (1793), p. 8, and Appendix II.
[1424] Brewer, 91; Bridges, I. 67.
[1425] Brewer, 472.